Perhaps the worst-kept secret in the world of secret agents, Adele confirmed what has been widely discussed and all but confirmed for weeks: that she'll be singing the theme for the upcoming James Bond film, "Skyfall."

On Tuesday, the singer tweeted a picture — without comment — of sheet music for a song called "Skyfall," which she wrote with her "Rolling in the Deep" co-writer, Paul Epworth. Shortly thereafter, a message on the James Bond Facebook page officially announced the single and included a statement from Adele.

"I was a little hesitant at first to be involved with the theme song for SKYFALL. There's a lot of instant spotlight and pressure when it comes to a Bond song," Adele said. "But I fell in love with the script and Paul [Epworth] had some great ideas for the track and it ended up being a bit of a no-brainer to do it in the end. It was also a lot of fun writing to a brief, something I've never done which made it exciting. When we recorded the strings, it was one of the proudest moments of my life. I'll be back combing my hair when I'm 60 telling people I was a Bond girl back in the day, I'm sure!"

The theme for "Skyfall" will debut online at 7:07 a.m. EST on Thursday. (That's 0:07 a.m. BST, October 5, in London, the 50-year anniversary of the first Bond film, "Dr. No.")

You can pre-order the single through a link on Adele's official website, which has now been replaced with a countdown to the official release and the art from the song's cover.

"Skyfall" opens in theaters on November 9.

Check out everything we've got on "Skyfall."